Method of making rail bonds



Feb. 28, 1939. c. -A. CADWELL METHOD OF MAKING RAIL BONDS Filed 001;. 24, 1935 2% mm m m m ma. w I M A Patented Feb. 28, 1939 METHOD or MAKING can. nouns Charles A. Cadwell, Cleveland Heights, Ohio, as-

signor to The Electric Railway Company, Cleveland, Ohio, a

Ohio

Improvement corporation of Application October 24, 1935, Serial No'.d46,559

7 Claims.

This invention relates, as indicated, to rail bonds, but has reference more particularly to rail bonds of the type in which the conductor is mechanically joined to the terminals, and to methods of manufacturing the same.

It has heretofore been proposed to mechanically join electrical conductors by means of a common sleeve, to be joined is these methods between which and the conductors interposed a frictional material, being characterized by the fact tive for joining a stranded conductor with a short heavy terminal, as in the manufacture of rail bonds, and in which the requirements as to strength and electrical conductivity of the joints are rather severe.

The present invention has for its primary object the provision of a method of mechanically joining the stranded of a rail bond,

conductor to the terminals by which method a. joint of high electrical conductivity and mechanical strength is secured.

Tqthe accomplishment of the foregoing and related ends, said invention, then, consists of the methods and means hereinafter fully described and particularly pointed out in the claims; the

annexed drawi ng and the following description setting forth for purposes of illustration, the invention as applied to the formation of a joint or union between the stranded conductor of a. rail bond and one of the terminals of such bond.

In said annexed drawing:-

Fig. 1 shows the first step in the formation of the joint between a stranded conductor and a terminal of a cross-sectional 2-2 of Fi 1; joint; Fig. 4 is rail bond; Fig. 2 is a transverse view of the joint, taken on the line Fig. 3 is a. view of the completed a transverse cross-sectional view of the completed joint, taken on the line 4-4 'of Fig. 3.

In accordance with conductor 5 is inserted into tubular exstranded tension 6 of a the invention, one end of a terminal I, which, in the present instance is in the form of a copper forging, and of the type adapted to be mechanically secured to a rail. The terminal I is preferably rigidly held in an upright position as shown in Fig. 1, with its lower end in a granular mate box or other receptacle containing rial which is to be used in the particles fillin process of forming the joint. The granular material is preferably a good conductor, such, for example, as an alloy of copper with aluminum, or silicon, but inthe formation of joints in which good conductivity is not of importance, 9. material 5 of lower conductivity may be used, such, for example, as a granulated form of carborundum, chromium or manganese.

It has been discovered that in practice, a brittle alloy of copper with, for example, aluminum or 10 silicon, when crushed to a fineness of about 80 mesh and finer, has a granular consistency which makes it admirably adapted for the purpose at hand.

With the conductor and terminal positioned as shown, granular material 8 of the character described in the preceding paragraph is poured into the interstices between the conductor 5 and the inner wall of the tubular extension 6, the portion of the conductor immediately above the tubular extension being preferably untwisted, as indicated by the arrow in Fig..l during the pouring operation, so as to cause the strands of the conductor to become slightly separated from each other. As a result of this untwisting operation, as the granular material will not only enter the interstices between the conductor and the wall of the tubular extension, but will also penetrate the conductor, the finer or dust-like particles entering the smaller interstices between the inner so strands of the conductor end and the coarser the larger spaces, the entire mixture of various sizes completely flooding all of the spaces within the end of the conductor, as shown in Fig. 2. The twisting motion causes the strands a of the conductor to breath in, as it were, the granular material, causing the latter to penetrate to the very core of the conductor.

The tubular extension i of the terminal is then compressed about the stranded conductor by. 40 means of dies orthe like, so as to reduce the normal section shown in Figs. 1 and 2 until it assumes a form somewhat as shown in Figs. 3 and 4. The compression causes the particles adjacent the inner wall of the extension to embed thema selves in said wall as well as in the strands comprising the outermost layer of the conductor and causes the remaining particles to embed themselves in the strands comprising the inner layers of the conductor, so that each strand is mechanlgo cally or frictionally joined with its adjacent strands, and the inner are anchored to the outer strands.

The result is an extremely strong joint between the conductor and terminals, this Joint being, in u strands of the conductor I Q fact, so strong that in tensile tests of rail bonds embodying such joints, the conductor usually ruptures intermediate its ends before the joints are in any way disturbed. Furthermore, when the granular material is a good conductor, it has been ascertained, as a result of various tests, that the rail bond has lesser electrical resistance than an equal length of the stranded conductor alone.

Furthermore, it will bereadily understood that the invention is not confined in its application to the manufacture of rail bonds, but may be advantageously employed wherever stranded conductors or cables are to be joined to each other or to a sleeve or the like.

Other forms may be employed embodying the features of my invention instead of the one here explained, change being made in the form or construction, provided the elements stated by any of the following claims or the equivalent of such stated elements be employed, whether produced by my preferred method or by others embodying steps equivalent to those stated in the following claims.

I therefore particularly point out and distinctly claim as my invention:--

1. The method of making a joint between a stranded conductor and a tubular member, which comprises inserting an end of said conductor into said member, then introducing in the space between said conductor and member a material of good electrical conductivity and in such finely divided form that it will penetrate the spaces between the strands of said conductor, and then pressing said member into intimate engagement with said conductor.

2. The method of making a joint between a stranded conductor and a tubular member, which comprises inserting an end of said conductor into said member, introducing a granular material into the space between said conductor and member, untwisting the portion of said conductor within said tubular member during the introduc-,

tion of said granular material so as to cause penetration of said material into the spaces between inner strands of the conductor, and then pressing said member into intimate contact with said conductor.

3. The method of making a joint between a stranded conductor and a tubular member, which comprises inserting an end of said conductor into said member, introducing a material of good electrical conductivity and in finely divided form into the space between said conductor and member, untwisting the portion of said conductor within said member during the introduction of said material in order to cause penetration of the particles of the material into the spaces between inner strands of the conductor, and then pressing said member into engagement with said conductor.

4. The method of making a joint between a stranded conductor and a tubular member which comprises inserting an end of said conductor into said member, then introducing into the space between said conductor and member an alloy of copper in such finely divided form that it will penetrate the spaces between the strands of said conductor, and then pressing said member into engagement with said conductor.

5. The method of making a joint between a stranded conductor and a tubular member which comprises inserting an end of said conductor into said member, introducing into the space between said conductor and member an alloy of copper, said alloy being in a form such that it will pass through an 80 mesh screen, and then pressing said member into engagment with said conductor.

6. The method of making a joint between a stranded conductor anda tubular member which comprises causing a material of good electrical conductivity and in finely divided form to adhere to the surface of and penetrate the spaces between inner strands of the conductor and then pressing said member into engagement with said conductor.

7. The method of making a joint between a stranded conductor and a tubular member which comprises applying a material of good electrical conductivity and in finely divided form to an end portion of said conductor in such a manner as to cause said material to penetrate the spaces between inner strands of the conductor and then pressing said member into engagement with said end portion of the conductor.

CHARLES A. CADWELL. 

